Lawn mower sharpener



De M 1948- o. G. CRAVER, sR I 2,456,39

LAWN MowER SHARPENER v Filed Jan, 51, 1947 2 sheets-sheet 1 LAWN MWER SHARPENER y Filed Jan. 51, 1947 2 Sheets-Sheet '2 Urville Brani Crau/EPST:

Atl/1 wleys Patented Dec. 14, 1948 UNITED STATE 7 Claims.

This invention relates to a power actuated lawn mower sharpener especially adapted for use in sharpening the blades of a reel type lawn mower and by means of which the rotatable blades may be sharpened to a uniform depth and bevel for uniformly cooperating with the fixed cutter blade of the mower.

More particularly, it is an object of the invention to provide a lawn mower Sharpener including driving means for revolving the reel of the lawn mower for moving the rotary cutter blades of the reel into and out of engagement with a sharpening stone and by which the blades will be uniformly sharpened.

Still another object of the invention is to provide a Sharpener including a driving connection from a prime mover to the lawn mower reel and to the sharpening stone, whereby the stone or other sharpening element will be revolved simultaneously with the reel for insuring a uniform wearing of the stone and accordingly a uniform sharpening of the blades.

Still another object of the invention is to provide means for adjustably positioning the sharpening stone and by means of which both ends of the stone are adjusted uniformly for accurately positioning the stone or other sharpening element relatively to the reel blades.

Still another aim of the invention is to provide a Sharpener for a lawn mower of extremely simple construction, capable of being economically manufactured and sold and which may be manipulated and adjusted with accuracy by an unskilled operator for insuring an accuracy in the sharpening of the rotary blades of a lawn mower.

Various other objects and advantages of the invention will hereinafter become more fully apparent from the following description of the drawings, illustrating a preferred embodiment thereof, and wherein:

Figure 1 is an end view in elevation looking toward the outer end of the Sharpener and showing it in an operative position for sharpening the blades of a reel type lawn mower;

Figure 2 is a side elevational View thereof looking from left to right in Figure 1;

Figure 3 is a top plan view of the Sharpener;

Figure 4 is an enlarged fragmentary perspective view of a portion of the Sharpener, and

Figure 5 is an enlarged transverse sectionalview taken substantially along a plane as indicated by the line 5 5 of Figure 3.

Referring more specifically to the drawings, the numeral 6 designates a portion of a table top or bench ormay constitute a .separate base of the Sharpener, designated generally 'l and comprising the invention.

As best seen in Figure 1, one end of the base 6 is provided with a pair of brackets 8 which are secured thereto in spaced relationship and each 0f which brackets 8 connects an upright supporting arm 9 to the base Ii. A cross arm 1t, as best seen in Figures 3 and 4, is connected to the upper end and outer side of each supporting arm d by a nut and wing bolt fastening lI and the abutting face portionsvof the uprights 9 and supporting arms Ill are serrated, as seen at I2 to insure the retention of the supporting arms Ill in adjusted positions relatively to the uprights 9 when the nut and wing bolt fastenings I I are tightened. The supporting arms It are provided with longitudinally extending laterally disposed slots I3 each of which is adapted to slidably receive the shanks of a plurality of headed nut and bolt fastenings Ill which slidably engage the slots I3 and which extend through and are secured to supporting arms I5, one of which supporting arms I5 is mounted partially in overlapping relationship to each supporting arm IIJ and on the outer side thereof. It will thus be readily apparent that the supporting arms I5 form extensions of the arms Ill and are slidably connected thereto by the slots I3 and fastenings It to enable the arms I5 to be extended or retracted relatively to the arms IIJ.

The arms 15 are each provided with an outwardly projecting bracket arm I6 having a threaded bore Il extending transversely therethrough for threadedly engaging a feed screw I8 which is associated with each support Ill, I5. The supporting arms I0 are each provided with a bearing arm I9 which projects outwardly therefrom on the opposite side of the fastening II to the arm I5 thereof and which is provided with a bearing opening 2B which aligns with the threaded bore I'I on the associated supporting arm I5 and for receiving a portion of the unthreaded, opposite end of feed screw I8 thereof. Retaining collars 2l are carried by each feed screw I8 on opposite sides of its bearing arm I9 to prevent any reciprocation of the feed screw relatively to said bearing arm. A bevel gear 22 is keyed to the terminal of the unthreaded end of each feed screw Ill and said bevel gears are disposed on the outer sides of the bearing arms I9.

The supporting arms It, at the ends thereof remote to the arms I5, are provided with bearings 23 which project longitudinally from said ends for journaling a shaft 2t which is disposed transversely to the supports I, I5. The shaft .2li carries retaining collars 25 which bear against the outer sides of the bearings 23 to prevent reciprocatory movement of shaft 24 relatively to said bearings. A bevel gear 25 is keyed to each end of the shaft 24 and said bevel gears 26 mesh with the adjacent bevel gears 22. Either of the feedscrews i8 may be provided with an extension 27 which extends from the bevel gear 22 thereof and to which is connected a crank 28, by means of which said feed screw i8 may be revolved for revolving the other feed screw I8 and shaft 24 through the bevel gears 22 and 26 so that the arms l5 will be simultaneously extended or retracted relatively to the arms l and to uniform distances.

The arms I5, outwardly of the supporting arms I3, are connected by a cross brace 29 and therebeyond are provided with `transversely disposed aligned bearings 3B for journaling a shaft 3l which extends therebetween. A sharpening stone 32 of substantially circular cross section is pro- -vided with a .central bore Y33 extending longitudinally therethrough and through which theshaft 3l extends for Ymounting .the stone 32 between `the bearings 3Q. The stone 32 is connected for k*rotation with-the shaft 3l by means of one or a plurality of keys or splines 34, as seen in Figure 5.

The supports I3, l extend `from the uprights 9 inwardly with respect to the base 6 and are disposed thereover and normally are inclined downwardly and-toward the base 6. -Beyond and beneath the sharpening stone 32, a pair of clamps 35 are detachably securedby `fastenings 36 to the upper side of the base B land jare adapted to detachably engage and clamp the stationary cutter blade 31 of a lawn mower l3,8 Afor positioning the reel 33 thereof above the base 6 and beneath the sharpening stone 32.

An electric motor 49 is 4fastened to the upper side of the base 3 behind the clamps 35 and is provided with a driven shaft having a belt pulley vil keyed thereto. One of vtheground wheels of the lawn rnower 38 is removed from the axle 42 thereof and is replaced by a belt pulley 43 which aligns with thebelt pulley .4I and over which an endless beltll is trained for revolving the reel `39 from the motor 4B. A second belt pulley 45 is keyed to the axle 42,.outwardly of the belt pulley 43 and beneath a belt pulley 46 which is keyed to one end of the shaft 3|. An endless belt 47 is trained over the pulleys 45 and 46 for rotating the Sharpener stone 32 in the same-direction that the reel 39 is revolved.

From the foregoing, it will be readily apparent that the nut and wing bolt fastenings l'may be loosened for adjusting the supports lll, l5 relatively to the uprights 3 so that the under side of the'stone 32 will be disposed substantially at the level of the top of the reel 39 Kor slightly therebeneath. Thecrank 28 can then be actuated for extending or retracting the supporting arms I5 relatively to thearms i3 for positioning the perip hery of the stone v32 in engagement with the cutting edge of one-of the rotary cutter blades 430i the reel 39. The motori 40 is then actuated to drive Athe pulleys-4,f43f45and 46, the belts 44 and 41 andthe reel 39 and sharpening stone 32 in a counterclockwise direction, as seen in Figure 2, or in-theopposite direction to the direction that the reel 39 will revolve in the normal operation of the lawn mower 38. As the reel 39 is thus revolved, the outer cutting edges of its blades 48 will move into and out of engagement with the rotating sharpening stone 32, which is of sul- Vcient length to engage said `blades from end to end thereof, for uniformly grinding and beveling 4 the cutting edges of the blades 48 for sharpening said blades to uniform dimensions relatively to the reel 39 so that the cutting edges of all of the blades i8 will coact uniformly with the cutting edge of the stationary blade 3l when the lawn mower 38 is thereafter used in a conventional manner. It will be readily obvious that the sharpening stone 32 by being disposed slightly in front of the vertical center of the reel 39, may be advanced-toward said reelby operation of the crank 28 and during the sharpening operation to insure that all portions of all of the cutting edges of the `blades 48 are engaged and sharpened by the stone ksup-porting base, means for detaohably support- .ing a .reel type Ylawn mower thereon, driving means partiallysupportedby said base and adapted to be connected tothe lawn vmower axle for- `revolving the .lawn mower reel, a pair oiuprights connected to and extending upwardly from said base, supporting members projecting trom said uprights and-in a directionftoward the reel, and a sharpening stone disposed between the free ends of said supportingmembersand positioned to engage and `sharpen the cutting edges of the rotary blades of the reel, when said reel is revolved, and means for extending and retraoting said supporting Amembers for adjustably moving the sharpening stone toward and away from the rotary blades.

2. YIn a Sharpener for reel type lawn mowers, a

suppOrtingbaSe, means for detachably supporting arreel type lawn mower thereon, driving means partially supported by said base and adapted to be connected to the lawn mower axle for revolving the lawn mower reel, a pair of uprights connected to and extending upwardly from said base,

supporting members projecting `from said uprights and in a direction toward the reel, and .a sharpening stone disposed between the free ends of said supporting members andpositioned to engage and sharpen the cutting edges of the rotary blades of the reel, when said reel is revolved, each of said supporting members being formed of extensible sections, and manually actuated means for-simultaneously and uniformly adjusting the extensible sections of the supportingmembers for adjustably positioning the Vsharpening stone relatively to the rotary blades.

3. In a Sharpener for-reel type lawn mowers, a supporting base, means for detachably supporting a reeltype lawn mower thereon, driving ineans partially supported by saidbaseand adapted to be connected tothe lawn mower axle for revolving thelawn mower reel, .a pairof uprights connected to and extending. upwardly from said base, supporting members projecting from said uprights and in a direction toward the reel, and a sharpening stone disposed between the free ends of said supporting members and positioned to engage and sharpenthe cutting edges ofthe rotary blades of thereel, when said reel is revolved, and means for'angularly adjusting said supporting members relatively to the uprights for adjustably positioningthe sharpening stone relatively .to the cutting edges ofthe .rotary blades, eachrof said `supporting members 1seing `formed of extensible sections,v and manually actua-ted means for simultaneously and uniformly adjusting the extensible sections of the supporting members for adjustably positioning the sharpening stone relatively to the rotary blades.

4. in a Sharpener for reel type lawn mowers, a supporting base, means for det-achably support-- ing a reel type lawn mower thereon, driving means partially supported by said base and adapted to -be connected to the lawn mower axle for revolving the lawn mower reel, a pair of uprights connected to and extending upwardly from `said base, supporting members projecting from said uprights and in a direction toward the reel, and a sharpening stone disposed between the free ends of said supporting members and positioned to engage and sharpen the cutting edges of the rotary blades of the reel, when said reel is revolved, and means for angularly adjusting said supporting members relatively to the uprights for adjustably positioning the sharpening stone relatively to `the cutting edges of the rotary blades, each of said supporting members being formed of extensible sections, and manually actuated means for simultaneously and uniformly ladjusting the extensible sections of the supporting members for adjustably positioning the sharpening stone relatively to the rotary blades, said last mentioned means comprising feed screws for extending and retracting the extensible sections of each of the supporting members, a transversely disposed shaft journaled by said supporting members, bevel gears connecting the ends of the transversely disposed shaft to corresponding ends of the feed screws, and a manually actuated crank for simultaneously rotating the feed screws and transversely disposed shaft.

5. In a Sharpener for reel type lawn mowers, a supporting base, means for detachably vsupporting a reel type lawn mower thereon, driving means partially supported -by said base and adapted to be connected to the lawn mower axle for revolving the lawn mower reel, a pair of uprights connected to and extending upwardly from said base, supporting members projecting from said uprights and in a direction toward the reel, and a sharpening stone disposed between the free ends of said supporting members and positioned to engage and sharpen the cutting edges of the rotary blades of vthe reel, when said reel is revolved, said sharpening stone having a shaft extending longitudinally therethrough and keyed thereto, said sharpening stone being 4substantially circular in cross section, the sharpening Istone shaft being journaled in said supporting members and having a belt pulley on one end thereof, a belt pulley keyed to one end of the reel axle, a belt connecting said belt pulleys for cau-sing the sharpening lstone to `be revolved simultaneously with and in the same direction as the lawn mower reel.

6. A lawn mower Sharpener as in claim 5, said supporting member being formed of extensible sections and being provided with feed screws for extending and retracting .the extensible sections of each of the supporting members, a transversely disposed shaft journaled by said supporting members, bevel gears connecting the ends of the transversely disposed shaft to corresponding ends of lthe feed screws, and a manually actuated crank for simultaneously rotating the feed screws and transversely disposed shaft.

7. A lawn mower Sharpener as in claim 5, said supporting member being formed of extensible sections and being provided with feed screws for extending and retracting the extensible sections of each of the supporting members, a transversely disposed shaft iournaled by said supporting mem- |bers, bevel gears connecting the ends of the transversely disposed shaft to corresponding ends ofthe feed screws, and a manually actuated crank for simultaneously rotating the feed screws and transversely disposed shaft, said sharpening stone being of a length equal to or greater than the length of said rotary blades.

ORVLLE GRANT CRAVER, SR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 556,868 Schureman Mar. 24, 1896 1,389,588 Klay Sept. 6, 1921 1,866,794 Bierman July 12, 1932 

